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A G ELLIS AND J. L. THOMPSON.

' TRANSFORMER.

v APPLICATION FILED NOV- R1917.

1,317,280. Patentedsept 30,1919.

WITNESSES v ATTORNEY ESTINGHOUSE EL'EC .L ENNSYLVANIA.

L. THOIMPSOIDZ'; OF STRETFFL stars, or 'BO'W'DON, Ann Jot-in;

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Specificatioi'i of Letters Patent.

Patented Sent. so, rare.

.lpplication filed November 7, 1917. Serial No. 200,665.

To all whom it may com-em:

lie it known that we, ALFRED Ga ELLIS, a subject of the King of Great Britain, and a resident of Bowdon, in the county of Chester and country of England, and JOHN L. T H031 r sen, a subject of theliing of Great Britain, and a resident of Stretford, in the county of Lancaster, and country of England, have invented a new and useful Improvement in Transformers, of which the following is a specification.

Uur invention relates to electrical transformers and it has special relationto those commonly known as core-type transformers which possess high internal reactance.

More particularly, our invention relates to a transformer havingconcentric primary and secondary coils between which magnetic shunts are disposed for the purpose of securing a high reactive-voltage drop in the transformer.

Heretofore, it has been the practice to construct a magnetic shunt adapted to be placed between the high and the low-tension coils'of a transformer in such a manner that the planes of the laminae comprising the shunt were parallel to the surfaces of the coils, assuming that the coils were circular. reluctance of such a shunt, it was divided by planes, perpendicular to. the axes of the coils, into sections separated from each other-by air-gaps.

It has been found that eddy currentscir culate in a magnetic shunt of this characten which increase the internal losses of the transformer. It is our opinion that these eddy currents are generated by reason of the leakage magnetic flux lines emerging from the body of the magnetic shunt at right angles to the'surfaces or planes of the laminee. Of course, the extensive flat surfaces of the laminm permit the eddy currents to reach appreciably high values.

In the present lnvention, we endeavor'to overcome this objection to magnetic shunts formed of laminated material by arranging the laminations in such manner that the magnetic-lealrage-fiux lines will emerge at the exposed edges of the laminae instead of at the side faces thereof.- In this manner, the eddy currents which naturally tend to circulate in planes perpendicular to thedirection of flow of the magnetic flux lines .sh'own in Fig. 2.

In order to increase the magnetic are very much reduced, with a consequent reduction in the transformer losses and,

ing one leg of a core-type transformerwhich I is provided with magnetic shunts constructed in accordance with our invention; Fig, 2 is a sectional view, similar. to that of Fig. 1, showing a modified form of a portion of a core-type transformer embodying our invention; and Fig. 3 is a developed side View of a portion of one of the magnetic shunts Referring to Fig. 1, a "core-leg 1 of a transformer core member of rectangular cross sectionis embraced by an inner coil 2 having two of its opposite sides flattened in order to more closely embrace the adjacent sides of the core leg. The coil 2 is a part of the secondary or low-tension winding of the transformer. Aniouter cylindrical coil 3, which is a part of the hightension or primary winding, embraces the core leg 1 and the coil 2 and thereby provides segmental spaces between it and the flattened portions of the'coil 2, as shown. In these segmental spaces, magnetic shunts 4: are interposed, said shunts being formed of magnetizablelaminations havmg their planes parallel to those of the laminae formving the core leg 1 and perpendicular to the flat or plane faces of the inner coil of the transformer. The laminae constituting the magnetic shunts 4 are threaded on rods 5 and are clamped together to form a bundle. A magnetic shunt may be built up a number of such bundles extending from end to end of the core leg 1, adjacent bundles being separated by intervening spacers of non-magnetic material, if desired, in order to increase the magnetic reluctance of the shunt.

The bundles of laminzemay be clamped between blocks or strips of wood, or other suitable material 6, as indicated. As shown in Fig. 1, the laminae forming the shunts are of two sizes, as indicated at 7 and 8,

so that a considerable portion of the available space may be occupied by the Obviously, the laminae may be of any desired number of graduated sizes. The strips 6, between which the laminae are clamped, may besupported in accordance with the general design of the transformer to which the present invention is applied.

In Fig. 2, a secondary coil 9 and a primary coil 10 are shown as of cylindrical form and concentrically disposed about a leg ll'of a transformer core. An annular space 12 is, in this manner, provided between the primary. and secondary coils. The

laminaeforming the magnetic shunts 13 are Y threaded on curved 'rods 14c and are preferably arranged 111 two sets, each set com prising a plurality of bundles and subtend-' mg substantially one-quarter of the periphery between the coils 9 and 10. The

- that such that axis.

bundles of laminae are spaced from one another by Jmeans of insulating strips 15 and each set of bundles is securely clampedbetween outer end frames 16 formed of wood Y or other suitable insulating material. It will be observed that the planes of the laminae -comprising' the magnetic shunts 14 are'paral'lel to the axis of the core leg ll and also planes, if extended, will meet in In other words, the laminae are radially disposed with reference to the coincident axes of the coils 9 and 10.

By referring tocFig. 3, which is a developed side'elevation of a portion of one of laminae. Since the tightly clamped together, they may be subject to vibration, This, however, may be prevented by dipping the loose ends of the bundles in Portland cement or other binding material which is not afl'ected the insulating oil in which the transformer may be immersed.

In transformers constructed according to our invention, the magnetic shunts may or maynot occupy the whole of the space be tween the primary and secondary coils. The remaining vacant spaces may form additional cooling ducts for air or circulating" The magnetic reluctance of paths for oi any suitable manner, in

are interposed besubstantially rathe shunts may be readily adjusted by varying the number of laminae in a bundle or by varying the number'of bundles and the air spaces between them, as will be readily understood without further description.

While we have shown and described one form of our invention, it will be understood that many modifications may be made there'- in without departing from the scope of the appended claims.

We claim as our invention:

1. In an electrical apparatus, the combination with concentric primary and secondary coils disposed upon a laminated core member, of magnetizable laminae interposed between said coils and having their planes approximately parallel to the coincident axes of said concentrically arranged coils.

2. Inan electrical apparatus, the combination with concentric primary and secondary coils disposed upon a laminated core member, of magnetizable laminae interposed between said coils and having their planes approximately coinciding with the planes of the flow lines of the magnetic leakage flux between said coils.

3. In an electrical apparatus, the combination with, concentric primary and secondary windings disposed upon a laminated core member, of magnetizable laminae interposed therebetween and having their planes approximately coinciding with the planes of the flow lines of the magnetic leakage flux through one of said windings.

4%. An electrical transformer comprising a magnetizable laminated core member, primary and secondary coils embracing said core member, and magnetizable laminae in terposedbetwen said coils, said laminae having their planes substantially parallel with those of the laminae forming saidcore memher.

5. An electrical transformer comprising a m'agnetizable core member, primary and secondary coils embracing a leg of said core member, and magnetizable laminae interposed between said coils, said laminae having their planes approximately parallel to the axis of the core leg embraced by said coils.

In testimony whereof, we have hereunto subscribed our names this first day of October, 1917.

ALFRED G. ELLIS.

JOHN L. THOMPSON. Witnesses:

A. J. Onmsns, l M. B. A. LOUDER. 

